Method and apparatus for EMR treatment

ABSTRACT

A method and apparatus are provided for performing a therapeutic treatment on a patient&#39;s skin by concentrating applied radiation of at least one selected wavelength at a plurality of selected, three-dimensionally located, treatment portions, which treatment portions are within non-treatment portions. The ratio of treatment portions to the total volume may vary from 0.1% to 90%, but is preferably less than 50%. Various techniques, including wavelength, may be utilized to control the depth to which radiation is concentrated and suitable optical systems may be provided to concentrate applied radiation in parallel or in series for selected combinations of one or more treatment portions.

RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 10/033,302 entitled “Method and Apparatus for EMR Treatment,”which was filed on Dec. 27, 2001, and herein incorporated by reference,which, in turn, claims priority from provisional application Ser. No.60/258,855 filed Dec. 28, 2000.

FIELD OF THE INVENTION

This invention relates to methods and apparatus for usingelectromagnetic radiation (EMR) for various therapeutic treatments andmore particularly to methods and apparatus for dermatological treatmentby use of spatially confined and concentrated EMR to create areas oftreatment or damage substantially surrounded by areas of sparing.

BACKGROUND OF THE INVENTION

Various forms of electromagnetic radiation, particularly opticalradiation, both coherent and non-coherent, have been utilized for manyyears for a variety of medical treatments, and in particular fordermatology treatments. Such treatments include, but are by no meanslimited to, removal of unwanted hair, skin rejuvenation, removal ofvascular lesions, acne treatment, treatment of cellulite, pigmentedlesions and psoriasis, tattoo removal, treatment of skin and othercancers, etc. Most of these treatments have involved in one way oranother the use of a process known as selective photothermolysis (Seefor example Anderson R R, Parrish J., Selective photothermolysis:Precise microsurgery by selective absorption of the pulsed radiation.Science 1983; 220: 524-526), this process involving irradiating a targetarea to be treated with radiation at a wavelength preferentiallyabsorbed by a chromophore, either a natural chromophore or artificiallyintroduced chromophore, in the target area, the heating of thechromophore either directly or indirectly effecting the desiredtreatment.

While these techniques are useful for many of the indicatedapplications, these techniques have a number of significant limitations.First, treatments which are performed over a relatively large area, suchas skin rejuvenation and hair removal, particularly skin rejuvenation,can cause varying degrees of skin damage over a substantial treatmentarea. In particular, such treatments can sometimes result in adetachment of skin layers. These relatively large areas of skin damagecan frequently take several weeks or more to heal, and follow-uptreatments can normally not be performed during this period. It would bepreferable if these procedures could be performed in a manner whichwould result in smaller, spaced areas of damage which heal more quickly,this enhancing both patient comfort and the ability to more quicklyperform follow-up treatments. Further, many treatments, such as forexample hair removal and wrinkle removal, only require that thetreatment be performed in small portions or regions of a much largertreatment area; however, current techniques of treatment generallyrequire that the treatment be performed over the entire treatment arearather than in only the selected regions of the treatment area requiringtreatment.

Another potential problem is the need for a chromophore in the targetarea which selectively absorbs the applied radiation to generate theheat required for treatment. First, to the extent the regions above thetreatment area contain a chromophore which preferentially absorbs orotherwise absorbs the applied radiation, such chromophores are alsoheated, and care must be exercised in any treatment to assure that suchheating does not result in epidermal or dermal damage. Various forms ofcooling of such overlying regions, sometimes aggressive cooling, arefrequently required to permit such treatments to be performed withoutdamage to the overlying skin. For example, for hair removal or othertreatments where melanin is targeted, heating of melanin in theepidermis, particularly at the dermis-epidermis (DE) junction, is aproblem. Where the chromophore being targeted is water, substantiallyall tissue in the treatment area and thereabove will be absorbing theradiation and will be heated, making controlled treatment of a selectedbody component difficult, and increasing the likelihood of unwantedperipheral damaged.

Another problem with selective photothermolysis is that the wavelengthselected for the radiation is generally dictated by the absorptioncharacteristics of the chromophore utilized. However, such wavelengthsmay not be optimal for other purposes. For example, skin is a scatteringmedium, but such scattering is far more pronounced at some wavelengthsthan at others. Unfortunately, wavelengths preferentially absorbed byfor example melanin, a frequently used chromophore, are also wavelengthsat which substantial scattering occurs. This is also true for thewavelengths typically utilized for treating vascular lesions. Photonabsorption in skin also varies over the optical wavelength band,wavelengths dictated by selective photothermolysis frequently beingwavelengths at which skin is highly absorbent. The fact that wavelengthstypically utilized for selective photothermolysis are highly scatteredand/or highly absorbed limits the ability to selectively target bodycomponents, and in particular, limits the depths at which treatments canbe effectively and efficiently performed. Further, the fact that much ofthe energy applied to a target region is either scattered and does notreach the body component undergoing treatment, or is absorbed inoverlying or surrounding tissue to cause undesired and potentiallydangerous heating of such tissue, results in optical dermatologytreatments being relatively inefficient. This low efficiency for suchtreatments means that larger and more powerful EMR sources are requiredin order to achieve a desired therapeutic result and that additionalcost and energy must be utilized to mitigate the effects of thisundesired heating by surface cooling or other suitable techniques. Heatmanagement for the more powerful EMR source is also a problem, generallyrequiring expensive and bulky water circulation or other heat managementmechanisms. Further, since chromophore concentration in a target (forexample melanin in the hair) varies significantly from target to targetand from patient to patient, it is difficult to determine optimum, oreven proper parameters for effective treatment of a given target usingselective photothermolysis. High absorption by certain types of skin,for example dark skinned individuals or people with very tanned skin,often makes certain treatments difficult, or even impossible, to safelyperform. A technique which permitted all types and pigmentations of skinto be safely treated, preferably with little or no pain, and preferablyusing substantially the same parameters, is therefore desirable.

Still another problem with existing treatment is that the amount ofenergy which can be applied to the treatment area, even where damage tothe epidermis, skin scarring or other damage is not an issue, isfrequently limited by pain experienced by the patient. Ideally, EMRdermatology procedures, which are typically for cosmetic purposes,should be painless or substantially painless. While if the procedure isbeing performed by a physician, pain may be controlled by the use of alocal anesthetic, or even by putting the patient to sleep, there arerisks in the use of any anesthetic, and the use of needles to administera local anesthetic is undesirable for cosmetic procedures. It wouldtherefore be preferable if patient pain could be substantially reducedor eliminated without the need for such procedures, while stillpermitting sufficient radiation to be applied to achieve a desiredtherapeutic result.

There are also occasions where microsurgery is required or desired on apatient's skin, particularly near the skin surface, where the area to betreated is of a size in the micron range, for example 10 microns, a sizewhich cannot be treated with a scalpel. Existing EMR devices forperforming microsurgery are also not adapted for performing surgery onsuch small targets. A need therefore exists for improved techniques forperforming such fine microsurgery.

Further, while EMR techniques are available for treating some of theconditions indicated above, such techniques do not currently exist fortreating scars, including acne scars, chicken pox scars and the like,for bumps in the skin resulting from scar tissue, for stretch marks, fortreating certain parasites, etc. An effective technique for treatingsuch conditions is therefore needed.

Still another problem is in the removal of tattoos or pigmented lesions,particularly close to the skin surface, where existing techniquesfrequently result in blistering and other skin problems. An improvedtechnique which would permit the fading of such tattoos or pigmentedlesions and/or the ultimate removal thereof in a gentle enough manner soas to not cause damage to the patient's skin or significant patientdiscomfort is also desirable. Similar techniques for treating variousskin blemishes are also desirable.

Finally, while techniques currently exist which are relatively effectivein treating large vascular lesions, such techniques are not as efficientin treating spider veins and other small veins. Similar inefficienciesexist where radiation is applied over a relatively large area of apatient's skin where treatment is required in only relatively smallportions of such area.

A need therefore exists for an improved method and apparatus for EMRtherapeutic treatments, and in particular for optical dermatologytreatments, which permit more selective treatment in target areas, andwhich do not rely on selective photothermolysis so that the wavelengthsutilized may be selected so as to be more efficient for delivery ofradiation to a desired target volume at a selected depth, and inparticular to selected portions of such a target volume, which portionsare preferably surrounded by portions which are not treated, and so thatproper parameters for treating a given target may be more easilydetermined.

SUMMARY OF THE INVENTION

In accordance with the above, this invention provides a method andapparatus for performing a treatment on a volume located at area anddepth coordinants of a patient's skin, the method involving providing aradiation source and applying radiation from the source to an opticalsystem which concentrates the radiation to at least one depth within thedepth coordinants of the volume and to selected areas within the areacoordinants of the volume, the at least one depth and the selected areasdefining three-dimensional treatment portions in the volume withinuntreated portions of the volume. The apparatus has the radiation sourceand an optical system to which radiation from the source is applied, theoptical system concentrating the radiation to at least one depth in thevolume and to selected areas of the volume, the at least one depth andthe areas defining the three-dimensional treatment portions in thevolume within untreated portions of the volume. For both the method andapparatus, the ratio of the treatment portions to the volume may bebetween 0.1% and 90%, but is preferably between 10% and 50%, and morepreferably between 10% and 30%. In each instance, the treatment portionsmay be cylinders, spheres, ellipsoids, solid rectangles or planes of atleast one selected size and thickness. The treatment portions may alsobe spaced lines of a selected length and thickness. The optical systemmay either apply radiation to all the treatment portions substantiallysimultaneously or the optical system may apply radiation to at leastselected treatment portions sequentially.

The patient's skin over at least one treatment portion may also bepre-cooled to a selected temperature for a selected duration, theselected temperature and duration for pre-cooling preferably beingsufficient to cool the skin to at least a selected temperature belownormal body temperature to at least the at least one depth for thetreatment portions. For selected embodiments, the skin is cooled to atleast the selected temperature to a depth below the at least one depthfor the treatment portions so that the at least one treatment portion issubstantially surrounded by cooled skin. The cooling may continue duringthe applying of radiation, and for this embodiment, the duration of theapplying of radiation may be greater than the thermal relaxation time ofthe treatment portions. The wavelength for the radiation source ispreferably selected so as not to be either highly absorbed or scatteredin the patient's skin above the volume on which treatment is to beperformed. For deeper depth coordinants, the optical system focuses to aselected depth below the at least one depth of the treatment portions inorder to achieve concentration at the desired depth coordinant in thepatient's skin. A selected condition in the volume on which treatment isbeing performed and/or the patient's skin above this volume may bedetected, the results of the detecting being utilized during theapplying of radiation to control the treatment portions to whichradiation is concentrated.

The applied radiation preferably has an output wavelength which is atleast in part a function of the at least one depth of the treatmentportions. More specifically, the wavelength of the applied radiation maybe selected as a function of the applied radiation as follows:depth=0.05 to 0.2 mm, wavelength=400-1880 nm & 2050-2350 nm, with800-1850 nm & 2100-2300 nm preferred; depth=0.2 to 0.3 mm,wavelength=500-1880 nm & 2050-2350 nm, with 800-1850 nm & 2150-2300 nmpreferred; depth=0.3 to 0.5 mm, wavelength=600-1380 nm & 1520-1850 nm &2150-2260 nm, with 900-1300 nm & 1550-1820 nm & 2150-2250 nm preferred;depth=0.5 to 1.0 mm, wavelength=600-1370 mn & 1600-1820 nm, with900-1250 nm & 1650-1750 nm preferred; depth=1.0 to 2.0 mm,wavelength=670-1350 nm & 1650-1780 nm, with 900-1230 nm preferred;depth=2.0 to 5.0 mm, wavelength=800-1300 run, with 1050-1220 nmpreferred.

The method and apparatus may also be utilized to treat a variety ofmedical conditions. Where a vascular lesion at a selected depth is beingtreated, treatment parameters, including the optical system and thewavelength of the applied radiation are selected so that the at leastone depth of the treatment portions are at the depth of the vessel beingtreated. Similarly, where the treatment is skin remodulation bytreatment of collagen or hair removal, treatment parameters, includingthe optical system and the radiation wavelength are selected so that theat least one depth is the depth of interdermal collagen and the depth ofat least one of the bulge and matrix of the hair follicle, respectively.The teachings of this invention may also be used to treat acne, totarget and destroy pockets of fat, to treat cellulite, for tattooremoval, for treating pigmented lesions, for treating hypotropic andother scars and other skin blemishes, and for treating various otherconditions in the skin.

The optical system utilized in practicing this invention may include anarray of optical elements to at least a plurality of which radiationfrom the source is simultaneously applied, each of the optical elementsconcentrating the radiation to a selected portion of the volume. Each ofthe optical elements may for example focus or concentrate to a line ofselected length and thickness, the lines for some of the elements beingat a selected angle to the lines of other of the elements. The opticalsystem may alternatively include apparatus for scanning radiationapplied to optical concentrating components so as to successively focusradiation to N of the treatment portions at a time, where N≧1. Theoptical system may instead include adjustable depth optical focusingcomponents, and a positioning mechanism for such optical focusingcomponents which moves the components to focus at successive treatmentportions. The apparatus may also include a mechanism which cools thepart of the patient's skin at least over the selected area coordinantsto a selected temperature, and controls which selectively operate thecooling mechanism to pre-cool this part of the patient's skin for aselected duration before application of radiation and/or duringapplication of radiation. The cooling mechanism and the controls maypre-cool the skin to a temperature and for a duration sufficient to coolthe part of the skin to at least a selected temperature below normalbody temperature to the at least one depth of the treatment portions ormay cool to a depth below the at least one depth of the treatmentportions, the treatment portions in the latter case being substantiallysurrounded by cooled skin. The apparatus may also include a detector forat least one selected condition in the volume and/or in a part of thepatient's skin above the volume and the optical system may operate inresponse to the detector to control the treatment portion of the volumeto which radiation is concentrated.

The invention also includes a method and apparatus for performing atreatment on a volume located at an area and depth coordinant of apatient's skin which includes providing a radiation source andpre-cooling the patient's skin over at least part of the area coordinantof the volume to a selected temperature for a selected duration, theselected temperature and duration being sufficient to cool the skin to adepth below the depth coordinant of the volume; and applying radiationto an optical system which concentrates the radiation to at least onedepth coordinant and to selected areas within the area coordinants todefine treatment portions in the volume, the treatment portions beingless than the total volume and each treatment portion being withinuntreated portions and being substantially surrounded by cooled skin.More specifically, a mechanism may be provided which cools the patient'sskin over the area coordinant to the selected temperature and controlsmay be provided for selectively operating the cooling mechanism topre-cool the skin for a selected duration before application ofradiation and/or during application of radiation, the mechanism andcontrols cooling to a temperature and for a duration sufficient to coolthe skin to at least a selected temperature below normal bodytemperature to at least a depth below the depth coordinant of thevolume. The cooling of the patient's skin by the cooling mechanism maycontinue during the step of applying radiation and the duration ofradiation application may be greater than the thermal relaxation time ofeach treatment portion.

Finally, the invention includes a method and apparatus for performing atherapeutic treatment on a patient's skin by concentrating appliedradiation of at least one selected wavelength at a plurality of selectedthree-dimensionally located treatment portions, which treatment portionsare within non-treatment portions.

The foregoing and other objects, features and advantages of theinvention will be apparent from the following more particulardescription of various embodiments of the invention as illustrated inthe accompanying drawings, the same or related reference numerals beingused for common elements in the various figures.

IN THE DRAWINGS

FIGS. 1-1B are top views of three optical systems involving arrays ofoptical elements suitable for use in delivering radiation in parallel toa plurality of target portions.

FIGS. 2-3C are side views of various lens arrays suitable for deliveringradiation in parallel to a plurality of target portions.

FIGS. 4-4C are side views of Fresnel lens arrays suitable for deliveringradiation in parallel to a plurality of target portions.

FIGS. 5-5B are side views of holographic lens arrays suitable for use indelivering radiation in parallel to a plurality of target portions.

FIGS. 6-6A are side views of gradient lens arrays suitable for use indelivering radiation in parallel to a plurality of target portions.

FIGS. 7-7B are top views of various matrix arrays of cylindrical lenses,some of which are suitable for providing a line focus for a plurality oftarget portions.

FIGS. 8-8C are cross-sectional or side views of one layer of a matrixcylindrical lens system suitable for delivering radiation in parallel toa plurality of target portions.

FIGS. 9-9B are a perspective view and cross-sectional side views,respectively, of a two layer cylindrical lens array suitable fordelivering radiation in parallel to a plurality of target portions.

FIGS. 10-13 are side views of various optical objective arrays suitablefor use in concentrating radiation to one or more target portions.

FIGS. 14-19 are side views of various deflector systems suitable for usewith the arrays of FIGS. 10-13 to move to successive target portions.

FIGS. 20 and 21 are side views of two different variable focus opticalsystem suitable for use in practicing the teachings of this invention.

FIGS. 22A and 22B are semi-schematic perspective and side viewsrespectively of a section of a patient's skin and of equipmentpositioned thereon for practicing the teachings of this invention.

DETAILED DESCRIPTION

Referring first to FIGS. 22A and 22B, a portion of a patient's skin 200is shown, which portion includes an epidermis 202 overlying a dermis204, the junction of the epidermis and dermis being referred to as thedermis-epidermis (DE) junction 206. Also shown is a treatment volume Vlocated at a depth d in the patient's skin and having an area A.Treatment volume V may contain one or more vascular lesions which are tobe destroyed or removed, may contain a plurality of hair follicles whichare to be either permanently destroyed, or at least be damaged so as toresult in temporary hair loss, or which are to be stimulated to causehair growth, may contain in the area below the DE junction collagenwhich is to be restructured by various means, for example by beingtemporarily destroyed to stimulate regrowth, particularly for skinrejuvenation and wrinkle removal, may contain a melanoma to be removed,a vascular lesion, pigmented lesion, port wine stain, psoriasis, scar,or other skin blemish or a tattoo to be removed, or some other bodilycomponent on which optical dermatology procedures are performed.

Also shown is a system 208 for delivering optical radiation to volume V.System 208 includes an EMR source 210, which source may be a coherentlight source, such as a solid-state laser, dye laser, diode laser, fiberlaser or other coherent light source, or may be an incoherent lightsource, for example a flash lamp, halogen lamp, light bulb or otherincoherent light source used to deliver optical radiation in dermatologyprocedures. Acoustic, RF or other EMF sources may also be employed insuitable applications. The output from source 210 is applied to anoptical system 212, which is preferably in the form of a deliver head incontact with the surface of the patient's skin as shown in FIG. 22B.Where an acoustic, RF or other non-optical EMR source is used as source210, system 212 would be a suitable system for concentrating or focusingsuch EMR, for example a phased array, and the term “optical system”should be interpreted, where appropriate, to include such system.

Various embodiments of an optical system 212 are discussed hereinafterand shown in the various figures. Generally, system 212 functions toreceive radiation from source 210 and to focus/concentrate suchradiation to a focused one or more beams 222 directed to a selected oneor more treatment or target portions 214 of volume V, the focus beingboth to the depth d and spatially in the area A. The energy of theapplied EMR is thus concentrated to deliver more energy to targetportions 214. Depending on system parameters, portions 214 may becylinders of selected diameter and thickness, spheres or ellipsoids, andfor one embodiment may have a square or rectangular cross-section. Theportions of each shape may extend through volume V or may be formed in asingle layer or staggered layers thereof. Target portions 214 may alsobe (a) relatively narrow strips which may either extend through volumeV, be formed in a single thin layer in volume V or be in staggeredlayers of the volume; or (b) may be one or more thin layers formed involume V. As will be discussed in greater detail hereinafter, opticalsystem 212 may focus to all or a selected subset of portions 214simultaneously, may contain some type of optical or mechanical-opticalscanner for moving radiation focused to depth d to successive portions214, or may generate an output focused to depth d and be physicallymoved on the skin surface over volume V, either manually or by asuitable two-dimensional or three-dimensional (including depth)positioning mechanism, to direct radiation to desired successiveportions 214. For the two later embodiments, the movement may bedirectly from portion to portion to be focused on or the movement may bein a standard pattern, for example a grid pattern, with the EMR sourcebeing fired only when over a desired portion 214.

A cooling element 215 is also included to cool the surface of skin 200over treatment volume V. As shown in FIG. 22A and 22B, cooling element215 acts on optical system 212 to cool the portion of this system incontact with the patient's skin, and thus the portion of the patient'sskin in contact with such element. Cooling element 215 may for examplebe a thermoelectric element, or may be a system for passing water,preferably chilled water, a gas, preferably a chilled gas, and possiblyeven a cryogenic gas, over such portion of the optical system. Othertechniques for cooling the surface of the patient's skin known in theart could also be used. Further, where optical system 212 is not incontact with the patient's skin, cryogenic spray cooling, gas flow orother non-contact cooling techniques may be utilized. A cooling gel onthe skin surface might also be utilized, either in addition to orinstead of, one of the cooling techniques indicated above.

System 208 also includes an optional detector 216, which may for examplebe a CCD camera or other suitable detector for a selected characteristicof the patient's skin. The output from detector 216 is applied to acontrol 218, which is typically a suitably programmed microprocessor,but may be special purpose hardware or a hybrid of hardware andsoftware. Control 218 controls both the turning on and turning off ofsource 210 and may also control the power profile of the radiation.Control 218 is also applied to optical system 212 to for example controlfocus depth for the optical system and to control the portion orportions 214 to which radiation is being focused/concentrated at anygiven time, for example by controlling scanning by the optical systemand/or the beam radiating therefrom. Finally, controls 218 are appliedto cooling element 215 to control both the skin temperature above thevolume V and the cooling duration, both for precooling and during anirradiation. TABLE 1 Depth Pulse of width damage, Wavelength range, μmNA range range, μm broad preferred broad preferred s 50- 400-1880 &   800-1850 & <3 0.2-1 <2 200 2050-2350    2100-2300 200- 500-1880 &   800-1850 & <3 0.2-1 <10 300 2050-2350    2150-2300 300- 600-1380 &   900-1300 & <2 0.2-1 <60 500 1520-1850 &     1550-1820 &  2150-2260   2150-2250 500- 600-1370 &    900-1250 & <2   0.2-0.6 <120 10001600-1820    1650-1750 1000- 670-1350 &  900-1230 <1.5   0.2-0.6 <1202000 1650-1780    2000-  800-1300    1050-1220 <1   0.2-0.4 <300 5000

TABLE 2 Depth Diame- of ter of Wave- Pulse damage, damage, length width,Energy, Focusing μm μm μm NA ms J depth, μm 300 50-100 2.2 0.3-0.5<10 >0.00015 400-600 300 50-100 1.7 0.3-0.5 <10 >0.0007 400-600 30050-100 1.3 0.3-0.5 <10 >0.003 400-600 300 50-100 1.54 0.3-0.5<10 >0.0003 400-600 300 50-100 1.208 0.4-1   <10 >0.016 400-600 30050-200 0.92 0.4-1   <10 >0.15 400-600 1000 50-200 1.7 0.3-0.4 <100 >0.011100-2000 1000 50-200 1.54 0.4 <100 >0.008 1100-2000 1000 50-200 1.3 0.4<100 >0.1 1100-2000 1000 50-200 1.208 0.4 <100 >0.4 1100-2000

TABLE 3 Depth of Diameter of Wavelength, Pulse Power, Focusing damage,μm damage, μm μm NA width, ms W depth, μm 500-1000 200-1000 2.20.3-0.5 >100 >0.5 600-1500 500-1000 200-1000 1.7 0.3-0.5 >100 >1.5600-2000 500-1000 200-1000 1.208 0.3-0.6 >3000 >1.0 600-2000 500-1000400-1200 0.92 0.3-0.6 >3000 >25.0 600-2000 2000-3500  1000-2000  1.2080.3-0.4 >10000 >1.5 4000-6000 

In accordance with the teachings of this invention, system 208 controlsa variety of parameters of the applied radiation. Data in Tables 1-3were found based on Monte-Carlo modeling of photon propagation in theskin using standard parameters of skin scattering and absorption fordifferent wavelength. These parameters include, but are by no meanslimited to:

1. The shape of treatment portions 214. Each of these portions may be athin disk as shown, may be an elongated cylinder which may for exampleextend from a first depth closer to DE junction 206 to a second deeperdepth or, as will be discussed later in conjunction with various opticalsystems to be described, may be a line focus, each of the lines having aselected length, width and orientation and adjacent lines being spacedby a selected amount. The orientation of the lines for the portions 214in a given application need not all be the same, and some of the linesmay, for example, be at right angles to other lines (see for exampleFIGS. 7A and 7B). Lines can by oriented around a treatment target forgreater efficacy. For example the lines can be perpendicular to a vesselor parallel to a wrinkle. Portions 214 may also be spherical,ellipsoidal and at least for one embodiment, may be a solid square orrectangle of selected thickness. The shape of portion 214 is dictated bythe combined parameters of the focused optical signal applied thereto,with the duration of application and to a lesser extent the wavelengthof the signal being significant factors in determining the shape of thetargeted portions. For example, it has been found that with a 1720 nmlaser operating at roughly 0.5 J to 2 J and having a pulse duration of0.5 to 2 ms, a generally cylindrically shaped portion 214 is obtained.Conversely, with a 1250 nm laser operating in the same energy range andhaving a pulse duration of 0.5 to 3 seconds, with an average of 1second, generally spherically-shaped target portions are obtained. Theparameters for obtaining a particular portion shape may be determined ina variety of ways, including empirically. By suitable control ofwavelength, focusing, spot size at the surface and other parameters, theportions 214, regardless of shape, may extend through volume V, may beformed in a single thin layer of volume V or may be staggered so that,for example, adjacent portions 214 are in different thin layers ofvolume V. The pattern of the target portions in volume V may also varywith application. Further, target portions 214 may also be (a)relatively narrow stripes which may either extend through volume V, beformed in a single thin layer or be staggered in different thin layers,with for example adjacent stripes being in different layers; or (b) maybe one or more thin layers formed in volume V. While all of the priorconfigurations for target portion 214 could be formed either serially orin parallel, the last configuration with multiple thin layers in thevolume V would probably need to be formed serially. The geometry ofportions 214 controls the thermal damage in the treatment portion. Sincea sphere provides the greatest gradient, and is thus the most spatiallyconfined, it provides the most localized biological damage, and maytherefore be the preferred target shape for applications where this isdesirable.

2. The size of the treatment portions 214. For a depth of approximately1 mm into the patient's skin, the minimum diameter of a portion 214, orthe minimum width of a line 214, is estimated to be approximately 100microns; however, much larger portions, several mm's or more, arepossible. For greater depths, the minimum sizes will be greater.

3. Center to center spacing between portions 214. The center to centerspacing is determined by a number of factors, including the size ofportions 214 and the treatment being performed. Generally, it is desiredthat the spacing between adjacent portions 214 be sufficient to protectthe patient's skin and facilitate healing of damage thereto, while stillpermitting the desired therapeutic effect to be achieved. In oneapplication, as little as 4% of the volume V was damaged (i.e. a 4% fillfactor); however, the damaged portions 214 would typically coversubstantially more of treatment volume V. While theoretically, the ratioof the combined volume of treatment portions 214 to the volume V (alsosometimes referred to as the fill factor) could be 0.1% to 90%, apreferred range for fill factor is 10% to 50% for some applications and10% to 30% for most applications. It is important that there be at leastsome area of sparing around each of the islands or areas oftreatment/damage 214 and that this area of sparing be sufficient topermit the skin to recover, such recovery being facilitated bymelanosome migration.

4. The depth d for the volume V. While it may be difficult to achieve asmall focal spot 214 at a depth much below 1 mm in a scattering mediumsuch as skin, focussing at depths of up to 4 mm, and perhaps even more,may be possible so long as a tight focus is not required and a largerportion size 214, perhaps several millimeters, is acceptable.

5. Focus Depth. While as may be seen from Table 1, depth d for volume Vand the focal depth of optical system 212 are substantially the samewhen focussing to shallow depths, it is generally necessary in ascattering medium such as skin to focus to a greater depth, sometimes asubstantially greater depth, in order to achieve a focus at a deeperdepth d. The reason for this is that scattering prevents a tight focusfrom being achieved and results in the minimum spot size, and thusmaximum energy concentration, for the focused beam being at a depthsubstantially above that at which the beam is focussed. The focus depthcan be selected to achieve a minimum spot size at the desired depth dbased on the known characteristics of the skin.

6. Wavelength. Both scattering and absorption are wavelength dependent.Therefore, while for shallow depths a fairly wide band of wavelengthscan be utilized while still achieving a focused beam, the deeper thefocus depth, the more scattering and absorption become factors, and thenarrower the band of wavelengths available at which a reasonable focuscan be achieved. Table 1 indicates preferred wavelength bands forvarious depths, although acceptable, but less than optimal, results maybe possible outside these bands.

7. Pulse Width. Normally the pulse width of the applied radiation shouldbe less than the thermal relaxation time (TRT) of each of the targetedportions 214, since a longer duration will result in heat migratingbeyond the boundaries of these portions. Since the portions 214 willgenerally be relatively small, pulse durations will also be relativelyshort as indicated in Table 1. However, as depth increases, and the spotsizes thus also increase, maximum pulse width or duration also increase.Again, the values given in Table 1 are maximum values for a given spotsize and shorter pulses may be used. Generally, thermal diffusion theoryindicates that pulse width τ for a spherical island should be τ<500D²/24 and the pulse width for a cylindrical island with a diameter D isτ<50 D²/16. Further, the pulsewidths can sometimes be longer than thethermal relaxation time of the target portion 214 if density of thetargets is not too high, so that the combined heat from the target areasat any point outside these area is well below the damage threshold fortissue at such point. Also, as will be discussed later, with a suitablecooling regimen, the above limitation may not apply, and pulse durationsin excess of the thermal relaxation time for a damage portion 214,sometimes substantially in excess of TRT, may be utilized.

8. Power. The required power from the radiation source depends on thedesired therapeutic effect, increasing with increasing depth and coolingand with decreasing absorption due to wavelength. The power alsodecreases with increasing pulse width.

9. Cooling. Typically cooler 215 is activated before source 210 toprecool the patient's skin to a selected temperature below normal skintemperature, for example 0 to 10° C., to a depth of at least DE junction206, and preferably to depth d to protect the entire skin region 220above volume V. However, in accordance with the teachings of thisinvention, if precooling extends for a period sufficient for thepatient's skin to be cooled to a depth below the volume V, and inparticular if cooling continues after the application of radiationbegins, then heating will occur only in the radiated portions 214, eachof which portions will be surrounded by cooled skin. Therefore, even ifthe duration of the applied radiation exceeds TRT for portions 214, heatfrom these portions will be contained and thermal damage will not occurbeyond these portions. Further, while nerves may be stimulated inportions 214, the cooling of these nerves outside of portions 214 will,in addition to permitting tight control of damage volume, also blockpain signals from being transmitted to the brain, thus permittingtreatments to be effected with greater patient comfort, and inparticular permitting radiation doses to be applied to effect a desiredtreatment which might not otherwise be possible because of the resultingpain experienced by the patient. This cooling regimen is an importantfeature of the applicants invention.

10. Numerical Aperture. Numerical aperture is a function of the angle θfor the focused radiation beam 222 from optical device 212. It ispreferable that this number, and thus the angle θ, be as large aspossible so that the energy at portions 214 in volume V where radiationis concentrated is substantially greater than that at other points involume V (and in region 220), thereby minimizing damage to tissue inregion 220, and in portions of volume V other than portions 214, whilestill achieving the desired therapeutic effect in the portions 214 ofvolume V. Higher numerical aperture of the beam increases safety ofepidermis, but it is limited by scattering and absorption of higherangel optical rays. As can be seen from Table 1, the possible numericalaperture decreases as the focus depth increases.

Thus, by judicious selection of the various parameters indicated aboveand others, one or more focused radiation beams 222 may be achieved tocreate islands of treatment/damage 214 in a treatment volume V at aselected depth d in the patient's skin. Preferred ranges of parametersfor achieving these objectives at various depths are provided inTable 1. Table 2 and Table 3 illustrate ranges of parameters at variousdepths for short pulses (i.e., pulses of less than 10 ms for superficialsmall targets and less than 100 ms for deeper depths) and for longpulses respectively. The values in Table 2 assume that deep coolingthrough volume V as described above is not being provided so that thepulse duration is limited by the thermal relaxation time of damageportions 214. Thus, at shorter depths, where smaller spot or focus areascan be achieved, for example a spot having a diameter of 50 μm, asassumed in Table 2, pulse widths of less than 10 ms are required andother parameters are selected accordingly. Conversely, for deeperdepths, tight focus cannot be achieved because of scattering, resultingin a significantly larger diameter for damage portions 214, and thus alarger thermal relaxation time for these portions. Therefore,substantially longer pulse widths can be provided, permitting requiredenergy to achieve the therapeutic effect to be provided over a longertime interval. This facilitates removal of heat from region 220, and inparticular from the epidermal portion 202 thereof and from DE junction206. It also permits a lower peak power source 210 to be utilized. FromTable 2, 3 it is also noted that the focus depth is indicated as greaterthan the depth d of the damage portions 214. The reasons for this havebeen discussed above.

While controls 218 can be preprogrammed to focus on selected portions214 in target volume V, another option is to use feedback, eithermechanically obtained by use of detector 216, or obtained by anoperator, generally optically, but possibly using other of the operatorsenses such as touch or hearing, to control the portions 214 in volume Vwhich are focused on. Assuming, for example, that detector 216 is a CCDimaging device, the location of hair follicles, vascular lesions, orother targeted components in volume V can be located and focused beams222 specifically directed to the locations of such components. Thus,assuming a hair removal treatment, detector 216 could locate each hairfollicle at the surface above volume V, and then focus a beam 222 toeach such follicle at a selected depth, for example, a depth of 1 mmwhere stem cells are located. The beam could also be focused to anextended depth along the follicle, for example, 0.7-3 mm to assuredestruction of all elements within the follicle required for permanentor substantially permanent hair removal, for example, destruction offollicle stem cells, without substantially damaging dermal tissuesurrounding the follicle or damage to the follicle matrix. This resultis most easily achieved if the cooling technique discussed above isutilized, with cooling extending below the treatment volume V so thateach follicle being treated is surrounded by cooled dermal tissue.

Feedback could also be used to track a blood vessel or other vascularstructure being treated or to track a wrinkle or wrinkles to be treatedby collagen restructuring. Further, while focused beams 222 can beautomatically positioned in response to outputs from detector 216 bycontrol 218, such feedback can also be achieved by the operator manuallyadjusting the position of optical system 212 to track and treat hairfollicles, vascular structures, wrinkles or the like.

More specifically, the scanner used could include three low power laserdiodes, preferably of different colors, used for detection and one highpower laser diode used for treatment. The scanner can, for example, beutilized both to detect the location of the blood vessel and the depthof the blood vessel. One of the three diodes used for detection may be ahigh power diode which can be operated in either a detection ortreatment mode and detection, in some instances, may be performed byonly one or two diodes, which diode or diodes may be also used fortreatment in some cases. A suitable scanner can be used to move thedetectors and/or treatment diode over a selected pattern. However, whilegalvanic scanners have been used in the past, a contact scanner isrequired for this application, since the desired focusing of the beamrequires contact, something which is not possible with a galvanicscanner. Again, the scanner can be programmed to trace a particularpattern to locate targets, and may be programmed to follow a target oncelocated, for example a vein, or the scan may be manually controlled.Where the scan is following a selected target, for example a bloodvessel, irradiation may occur at selected points along the blood vessel.It is generally necessary to coagulate a blood vessel at a selected oneor more points along the vessel in order to stop blood flow therein andkill the vessel. It should not be necessary to irradiate the entirevessel in order to effect destruction thereof.

Where a scanner is being used, the area scanned can be projected on ascreen, providing effective magnification, which facilitates either theselection of desired target points in a programmed scan or theperformance of a scan along a desired target such as a blood vessel.Multiple detectors, which may be filtered to provide different colors,can be utilized for detecting the depth of a target, for example theblood vessel, so that light can be focused to the appropriate depth fortreatment. Thus, scanning can be in three dimensions. Since depth is tosome extent controlled by wavelength, a fiber laser, the outputwavelength of which is programmable over a limited range, may beutilized to control skin depth both for detection and treatment. In eachinstance, the treatment may be effected solely by focusing radiation toa selected point, water at the point normally being what is heated, orby the effect of such focusing coupled with selective absorption by thedesired target at the wavelength utilized. The chromophor, whiletypically water, could also be blood or melanin. Further, when treatingblood vessels, since there is no need for hemoglobin as a chromophore,the vessel can be compressed during treatment, for example by applyingpressure to the vessel. This can permit denaturation and shrinkage ofthe vessel wall, which can result in a more permanent closure of thevessel and in the potential to permanently close larger vessels. Thelocation and size of the islands of treatment/damage can be adjusted fordifferent size, type and location of vessel. Similarly, for hairremoval, since melanin need not be targeted, there is no requirement forhigh melanin content in the hair shaft or follicle, facilitating theeasier treatment of gray and blond hair.

For port wine stains, wavelength can be in a range of 0.9 to 1.85 μm forwater absorption or 0.38 to 1.1 μm for hemoglobin absorption with a fillfactor of 10% to 80%, and preferably, 30% to 50%. The light source canbe an arc lamp with filtering and masking.

The teachings of this invention are also particularly adapted for skinrejuvenation treatments by collagen regeneration. In such treatments,since collagen is not itself a chromophor, a chromophor such as water inthe tissues or blood in the papillary dermis or below typically absorbsradiation and is heated to heat the adjacent collagen, causing selectivedamage or destruction thereof which results in collagen regeneration.Perturbing blood vessels in the region can also result in the release offibroblasts which trigger the generation of new collagen. While suchtreatments may be made only along the line of a wrinkle or other blemishto be treated, such treatment is typically performed over a relativelylarge area undergoing treatment. In accordance with the teachings ofthis invention, such treatments can be more effectively performed byheating selective portions 214, with perhaps a 30% to 50% fill factor,resulting in significant collagen regeneration with less trauma and painto the patient. Such procedure may be performed over a relatively largearea A or, utilizing techniques similar to those discussed above forblood vessels, may be performed by periodically firing a beam when overa wrinkle, the beam being traced in a predetermined pattern and firedonly when over selected points on the wrinkle, or being moved to track awrinkle and periodically fired while thereover. Also, as for othertreatments where the teachings of this invention are employed, healingoccurs relatively quickly so that a subsequent treatment, to the extentrequired, might generally be performed within a few weeks of an initialtreatment, and certainly in less than a month.

Typically, a bump in the skin occurs when collagen is heated, the bumpresulting from contraction of the collagen. Thus, this technique can beused not only to remove wrinkles but also to remove other skin blemishessuch as acne or chicken pox scars or other scars in the skin and mayalso be utilized for treating cellulite. While the bump may recede afterapproximately a month, the heating also increases thethickness-to-length ratio of the collagen in the area, thus increasingthe collagen thickness, resulting in much of the improvement from skinrejuvenation/blemish removal being reasonably permanent.

Other skin blemishes treatable by the teachings of this inventioninclude stretch marks, which differ from wrinkles in that these marksare substantially flush with the surface, the collagen shrinkage andregeneration as a result of heating reducing these marks. Hypotropicscarring, the raised scars which occur after surgery or certain wounds,can also be treated by reducing blood flow to the vessels of the scar inmuch the same way that port wine stains are treated above.

In addition to hair removal, treatment of vascular lesions, and skinresurfacing, the teachings of this invention can also be used to targetand destroy a sebaceous gland or glands, for example to treat acne, totarget and destroy pockets of subcutaneous fat, to treat cellulite andto do skin resurfacing on areas where such treatments cannot currentlybe performed, for example neck and hands, where the damage caused usingstandard skin resurfacing techniques does not normally heal. Thetreating of only small islands in such areas should leave sufficientundamaged skin structure for healing to occur. The teachings of thisinvention may, as indicated above, also be utilized for tattoo removal,for treating pigmented lesions, for treating hypotropic and other scars,stretch marks, acne and chicken pox scars and other skin blemishes andfor treating various other conditions which may exist in the patient'sbody at depths of less than approximate 4 mm, for example, various skincancers and possibly PFB. For skin tumors, a combination may be used ofa feedback system that localizes the position of the tumor and a roboticsystem that insures complete thermal destruction of the tumor. Psoriasismay be treated in substantially the same way with substantially the sameparameters as for port wine stain. The teachings may also be used totreat intredermal parasites such as larva migrans, which can be detectedand selectively killed using the teachings of the invention.

There are three general ways in which the invention may be utilized fortattoo removal. The first is by using a wavelength or wavelengthsabsorbed by the tattoo ink, preferably with short, high fluence pulses,to break up or destroy the ink in and between cells. The secondtechnique involves destroying the cells containing the ink, targetingeither the ink or water in the cells, causing the ink to be released andremoved by the body's lymphatic system. Here long pulses in themillisecond to second range, having low power and high energy, wouldtypically be utilized. In a third technique, an ablation laser would beused to drill 1 to 2 mm spots into the tattoo, ablating or vaporizingboth cells and tattoo ink in these areas. With a small fill factor, infor example the 10% to 80% range, and preferable the 10% to 30% range,such small damage spots heal well, permitting the tattoo to beprogressively lightened and ultimately removed for each of the threetreatments. A randomized pattern on each treatment is also preferable tointerference of the removal pattern.

A particular problem for which the teachings of this invention areparticularly adapted is the treating of birthmarks or other pigmentedlesions in the epidermis. Such lesions are generally difficult to treatwithout blistering using conventional treatment. By using islands ofdamage with a fill factor of 1% to 50%, and preferably 10% to 30%, andwith a spot size of 100 microns to ½ mm, it is possible to treat suchlesions without scarring. Since the treatment in this case is so closeto the surface, focusing is not necessary. A similar treatment, withsimilar fill factor could be used for treating port wine stains ortattoos, but in either of these cases, focusing would be required sincethe treatment is at a greater depth. In all cases, a first treatmentmight result in only the lightening of the treated area. Once thetreated portion has healed, which generally would occur in a few weeksto a month with an islands of damage treatment, one or more additionaltreatments can be performed to further lighten the treated area untilthe lesion, port wine stain, tattoo or the like is removed. In eachinstance, dead cells resulting from the treatment containingmelanosites, ink or the like, would be removed by the body, normallypassing through the lymphatic system.

Thus, a technique has been provided (a) which permits varioustherapeutic treatments on a patient's body at depths up to approximately4 mm, (b) which permits only islands of damage in three dimensions tooccur, thereby facilitating healing (by permitting continued blood flowand cell proliferation between skin layers and islands of damage 214)and reducing patient discomfort, (c) which permits targeting of specificcomponents for treatment without damage to surrounding parts of thepatient's body, thereby more efficiently using the applied radiationwhile also reducing peripheral damage to the patient's body as theresult of such treatment (d) which permits treatment of all skin typesusing substantially the same parameters for a given treatment, therebysimplifying treatment set-up and treatment safety, and (e) which permitsthe wavelength utilized for treatment to be optimally selected for thedepth of treatment, rather than being restricted to a wavelengthoptimally absorbed by a targeted chromophore. In fact, while thewavelengths selected for the teachings of this invention normally havesignificant water absorption, one of the criteria in selectingwavelengths is that they are not, particularly for deeper depths, highlyabsorbed, even by water, so that the radiation can reach desired depthswithout losing substantial energy/photons to absorption. Theconcentration of photons/energy at target portions 214 increases energyat these portions more than enough to compensate for reduced absorptionat the wavelength utilized. This invention thus provides an entirely newand novel technique for performing such treatments.

FIGS. 1-21 illustrates various optical components suitable for use inoptical system 212. In these figures FIGS. 1-9B illustrate varioussystems for delivering radiation in parallel to a plurality of targetportions 214. The arrays of these figures are typically fixed focusarrays for a particular depth d. This depth may be changed either byusing a different array having a different focus depth, by selectivelychanging the position of the array relative to the surface of thepatient's skin or to target volume V or by controlling the wavelength(s)of the radiation. FIGS. 10-13 show various optical objective arrayswhich may be used in conjunction with the scanning or deflector systemsof FIGS. 14-19 to move to successive one or more focused portions 214within target volume V. Finally, FIGS. 20 and 21 show two differentvariable focus optical systems which may, for example, be movedmechanically or manually over the patient's skin to illuminatesuccessive portions 214 thereon.

Referring to these figures in greater detail, FIGS. 1, 1A and 1B show afocusing element 1 on a substrate 3, the focusing element having aborder which is in a hexagonal pattern (FIG. 1), a square pattern (FIG.1A), and a circular or elliptical pattern (FIG. 1B). Standard opticalmaterials can be used for these elements. While the hexagonal and squarepatterns of FIG. 1 and FIG. 1A can completely fill the working area ofthe focusing element plate 4, this is not true for the element patternof FIG. 1B. Radiation from source 210 would typically be appliedsimultaneously to all of the focusing elements 1; however, the radiationcould also be applied sequentially to these elements by use of asuitable scanning mechanism, or could be scanned in one direction,illuminating/irradiating for example four of the elements at a time.

FIGS. 2 and 2A are cross-sectional views of a microlens system fused ina refracting material 8, for example, porous glass. The refractive indexfor the material of lenses 5 must be greater than the refractive indexof refracting material 8. In FIG. 2, beam 11 initially passes throughplanar surface 10 of refracting material 8 and is then refracted both byprimary surface 6 and by secondary surface 7 of each microlens 5,resulting in the beam being focused to a focal point 12. The process isreversed in FIG. 2A, but the result is the same.

In FIGS. 2B and 2C, the incident beam 11 is refracted by a primary lenssurface 6 formed of the refracting material 8. Surfaces 6 and 7 for thevarious arrays can be either spherical or aspherical.

In FIGS. 3 and 3A, the lens pieces 15 are mounted to a substrate and arein an immersion material 16. The refraction index of lens pieces 15 aregreater than the refraction index of immersion material 16. Immersionmaterial 16 can be in a gas (air), liquid (water, cryogen spray) or asuitable solid Gas and liquid can be used for cooling of the skin. Theimmersion material is generally at the primary and secondary planesurfaces, 13 and 14, respectively. In FIG. 3A, the primary surface 6 andsecondary surface 7 of each lens piece 15 allows higher quality focusingto be achieved. For FIGS. 3B and 3C, the lens pieces 15 are fixed on asurface of a refracting material 8, the embodiment of FIG. 3C providinga deeper focus than that of FIG. 3B, or that of any of other arraysshown in FIGS. 3A-3C for a given lens 15. The lens arrays shown in FIGS.3A-3C are a preferred lens arrays for practicing the teachings of thisinvention.

FIGS. 4-4C show Fresnel lens surfaces 17 and 18 formed on a refractingmaterial 8. Changing the profile of Fresnel lens surface 17 and 18, therelationship between the radius of center 17 and ring 18 of the Fresnelsurface, makes it possible to achieve a desired quality of focusing. Thearrays of FIGS. 4B and 4C permit a higher quality focusing to beachieved and are other preferred arrays. Surfaces 17 and 18 can beeither spherical or aspherical.

In FIGS. 5 and 5A, the focusing of an incident beam 11 is achieved byforming a holographic lens 19 (i.e., a photographic hologram) on asurface of refracting material 8. Holographic lenses 19 may be formed oneither of the surfaces of refracting material 8 as shown in FIGS. 5 and5A or on both surfaces. FIG. 5B shows that the holographic material 20substituted for the refracting material 8 of FIGS. 5 and 5A. Theholographic lens is formed in the volume of material 20.

In FIGS. 6 and 6A, the focusing elements are formed by gradient lenses22 having primary plane surfaces 23 and secondary plane surfaces 24. Asshown in FIG. 6A, such gradient lenses may be sandwiched between a pairof refracting material plates 8 which provide support, protection andpossibly cooling for the lenses.

FIGS. 7, 7A and 7B illustrate various matrix arrays of cylindricallenses 25. The relation of the lengths 26 and diameters 27 of thecylindrical lenses 25 can vary as shown in the figures. The cylindricallens 25 of FIGS. 7A and 7B provide a line focus rather than a spot orcircle focus as for the arrays previously shown.

FIGS. 8-8C are cross-sectional views of one layer of a matrixcylindrical lens system. The incident beam 11 is refracted bycylindrical lenses 25 (FIGS. 8 and 8A) or half cylinder lenses 29 (FIGS.8B and 8C) and focus to a line focus 28. In FIGS. 8B and 8C, thecylindrical lenses 29 are in the immersion material 16. Primary workingoptical surface 30 and secondary optical working surface 31, which maybe spherical or aspherical, allowing high quality focusing to beachieved. As shown in FIGS. 7-8C the line focuses for adjacent lensesmay be oriented in different directions, the orientations being at rightangles to each other for certain of the lenses in these figures.

In FIGS. 9, 9A and 9B, a matrix of focal spots is achieved by passingincident beam 11 through two layers of cylindrical lenses 32 and 35.FIGS. 9A and 9B are cross-sections looking in two orthogonal directionsat the array shown in FIG. 9. By changing the focal distance of primarylayer lens 32, having a surface 33, and secondary lens 35, having asurface 36, it is possible to achieve a rectangular focal spot of adesired size. Primary layer lens 32 and secondary layer lens 35 aremounted in immersion material 16. Lenses 32 and 35 may be standardoptical fibers or may be replaced by cylindrical lenses which may bespherical or aspherical. Surfaces 34 and 37 can be of optical quality tominimize edge losses.

FIG. 10 shows a one lens objective 43 with a beam splitter 38. The beam11 incident on angle beam splitter 38 divides and then passes throughthe refracting surfaces 41 and 42 of lens 43 to focus at central point39 and off-center point 40. Surfaces 41 and 42 can be spherical and/oraspherical. Plate 54 having optical planar surfaces 53 and 55 permits afixed distance to be achieved between optical surface 55 and focusingpoints 39, 40. Angle beam splitter 38 can act as an optical grating thatcan split beam 11 into several beams and provide several focuses.

In FIG. 11, a two lens 43, 46 objective provides higher quality focusingand numerical aperture as a result of optimal positioning of opticalsurfaces 41, 42 and 44. All of these surfaces can be spherical oraspherical. Optical surface 45 of lens 46 can be planar to increasenumerical aperture and can be in contact with plate 54. Plate 54 canalso be a cooling element as previously discussed.

FIG. 12 differs from the previous figures in providing a three lensobjective, lenses 43, 46 and 49. FIG. 13 shows a four lens objectivesystem, the optical surfaces 50 and 51 of lens 52 allowing an increasedradius of treatment area (i.e., the distance between points 39 and 40).

FIGS. 14, 14A and 14B illustrate three optical systems which may beutilized as scanning front ends to the various objectives shown in FIGS.10-13. In these figures, the collimated initial beam 11 impinges on ascanning mirror 62 and is reflected by this mirror to surface 41 of thefirst lens 43 of the objective optics. Scanning mirror 62 is designed tomove optical axis 63 over an angle f. Rotational displacement of anormal 64 of mirror 62 by an angle f causes the angle of beam 11 to bevaried by an angle 2f. The optical position of scanning mirror 62 is inthe entrance pupil of the focusing objective. To better correlatebetween the diameter of scanning mirror 62 and the radius of the workingsurface (i.e., the distance between points 39 and 40) and to increasethe focusing quality, a lens 58 may be inserted before scanning mirror62 as shown in FIG. 14A. Optical surfaces 56 and 57 of lens 58 can bespherical or aspherical. For additional aberration control, a lens 61may be inserted between lens 58 and mirror 62, the lens 61 havingoptical surfaces 59 and 60.

FIGS. 15, 15A and 15B are similar to FIGS. 14, 14A and 14B except thatthe light source is a point source or optical fiber 65 rather thancollimated beam 11. Beam 66 from point source 65, for example the end ofa fiber, is incident on scanning mirror 62 (FIG. 15) or on surface 57 oflens 58 (FIGS. 15A, 15B).

FIGS. 16 and 16A show a two mirror scanning system. In the simpler caseshown in FIG. 16, scanning mirror 67 rotates over an angle f2 andscanning mirror 62 rotates over an angle f1. Beam 63 is initiallyincident on mirror 67 and is reflected by mirror 67 to mirror 62, fromwhich it is reflected to surface 41 of optical lens 43. In FIG. 16A, toincrease the numerical aperture of the focusing beam, increase work areaon the skin and decrease aberration between scanning mirrors 62 and 67,an objective lens 106 is inserted between the mirrors. While a simpleone lens objective 106 is shown in this figure, more complex objectivesmay be employed. Objective lens 106 refracts the beam from the center ofscanning mirror 67 to the center of scanning mirror 62.

In FIG. 17, scanning is performed by scanning lens 70 which is movablein direction s. When scanning lens 70 is moved to an off center position73, optical surface 68 refracts a ray of light along optical axis 71 todirection 72.

In FIG. 18, scanning is performed by rotating lens 76 to, for example,position 77. Surface 74 is planar and surface 75 is selected so that itdoes not influence the direction of refracted optical axis 72. In FIG.19, scanning is performed by the moving of point source or optical fiber65 in direction s.

FIGS. 20 and 21 show zoom lens objectives to move the island of damageto different depths. In FIG. 20, a first component is made up of asingle lens 81 movable along the optical axis relative to a secondcomponent which is unmovable and consists of two lenses 84 and 87. Lens84 is used to increase numerical aperture. To increase numericalaperture, range of back-focal distance and decrease focal spot size,optical surfaces 79, 80, 82, 83 and 85 can be aspherical. The relativeposition of the first and second components determines the depth offocal spot 12.

FIG. 21 shows zoom lens objectives with spherical optical surfaces. Thefirst component is made up of a single lens 90 movable with respect tothe second component along the optical axis. The second component, whichis unmovable, consists of five lenses 93, 96, 99, 102, and 105. Theradius of curvature of surfaces 88 and 89 are selected so as tocompensate for aberrations of the unmovable second component. Again, thedepth of focus may be controlled by controlling the distance between thefirst and second components. Either of the lens systems shown in FIGS.20 and 21 may be mounted so as to be movable either manually or undercontrol of control 218 to selectively focus on desired portions 214 oftarget volume V or to non-selectively focus on portions of the targetvolume.

While the invention has been shown and described above with reference toa number of embodiments, and variations on these embodiments have beendiscussed, these embodiments are being presented primarily for purposesof illustration and the foregoing and other changes in form and detailmay be made in these embodiments by one skilled in the art withoutdeparting from the spirit and scope of the invention which is be definedonly by the appended claims.

1. A method of treating a subject's skin, comprising applying treatmentradiation to the skin so as to generate, following the application ofthe radiation, a plurality of treatment portions within a volume of theskin such that each treatment portion is separated from anothertreatment portion by an untreated portion of the volume, wherein saidtreatment portions comprise a fraction of said volume in a range ofabout 1% to about 50%.
 2. The method of claim 1, wherein said treatmentportions comprise a fraction of the volume in a range of about 10% toabout 30%.
 3. The method of claim 1, wherein said step of applyingtreatment radiation comprises focusing the radiation into said treatmentportions.
 4. The method of claim 1, wherein said step of applyingtreatment radiation comprises applying treatment radiation of one ormore wavelengths suitable for treating a vascular legion in said skinvolume.
 5. The method of claim 1, wherein said step of applyingtreatment radiation comprises applying treatment radiation of one ormore wavelengths suitable for treating a pigmented legion in said skinvolume.
 6. The method of claim 1, wherein said step of applyingtreatment radiation comprises applying treatment radiation of one ormore wavelengths suitable for remodulation of collagen structure in saidskin volume.
 7. A method for dermatological treatment of a patient'sskin, comprising concentrating treatment radiation onto a plurality ofcolumnar segments within a volume of the skin such that followingapplication of the radiation each columnar segment corresponds to atreatment portion separated from another treatment portion by anuntreated portion of said volume.
 8. The method of claim 7, wherein saidtreatment portions comprise a fraction of said volume in a range ofabout 1% to about 50%.
 9. The method of claim 8, wherein said treatmentportions comprise a fraction of said volume in a range of about 10% toabout 30%.
 10. The method of claim 7, wherein at least a portion of saidcolumnar segments extend from the skin surface to a depth below thesurface.
 11. The method of claim 10, wherein the depth of columnarsegments ranges from about 0.5 mm to about 4 mm.
 12. The method of claim7, wherein each columnar segment exhibits a cross-sectional diameter ina range of about 50 microns to about 1000 microns.
 13. The method ofclaim 7, wherein each columnar segment exhibits a cross-sectionaldiameter in a range of about 100 microns to about 0.5 millimeters.14.-17. (canceled)
 18. A method for dermatological treatment of apatient's skin, comprising applying radiation to the skin so as togenerate, following application of the radiation, a plurality ofperiodically located three-dimensional treatment portions within avolume of the skin such that each treatment portion is separated fromanother treatment portion by an untreated portion of the volume. 19.-43.(canceled)
 44. The method of claim 1, wherein at least some of thetreatment portions extend from the skin surface to a depth below thesurface.
 45. The method of claim 1, wherein the treatment portionscomprise damaged portions.
 46. The method of claim 1, further comprisingselecting said treatment radiation to have one or more wavelengths in arange of about 1520 nm to about 1820 nm.
 47. The method of claim 1,further comprising applying the treatment radiation to the skin in atemporal sequence.
 48. The method of claim 47, further comprisingemploying a scanner optically coupled to a source of treatment radiationfor applying the treatment radiation to the skin in said temporalsequence.